JP7199595B2 - maleimide copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a maleimide copolymer having excellent dispersibility during melt extrusion kneading.

ABS resin is a thermoplastic resin with acrylonitrile, butadiene, and styrene as main components. widely used for On the other hand, in applications where heat resistance is required, such as automobile interior materials, the heat resistance may be insufficient. Techniques for improving heat resistance include the following, and maleimide-based copolymers and α-methylstyrene-based copolymers are used (Patent Documents 1 and 2). In recent years, progress has been made in increasing the torque of twin-screw extruders and deepening screw grooves, making it possible to achieve high discharge rates. In the initial stage of melt-kneading, the plasticization of the solid resin progresses, but in order for the solid resin to start plasticizing, the air phase existing around the solid resin is eliminated and the solid resin is compressed until it approaches the true solid density. known to be necessary. For this reason, it is known that when powder is melt-kneaded, a high kneading pressure must be applied in order to efficiently eliminate the air phase and increase the bulk density in order to initiate plasticization.

JP-A-2003-41080 WO2010/082617

An object of the present invention is to provide a maleimide-based copolymer excellent in dispersibility during melt extrusion kneading.

(1) A powdery maleimide-based copolymer (A) having an average particle size of 75 µm or more and a sieve of 1000 µm or less of less than 5% by mass.
(2) The maleimide-based copolymer (A) according to (1), which has a glass transition temperature of 170 to 210°C.
(3) The maleimide copolymer (A) according to (1) or (2), which has a melt viscosity of 1000 Pa·s or more at 260°C and a shear rate of 120/sec.
(4) The maleimide-based copolymer (A) according to any one of (1) to (3) and at least one resin (B) selected from ABS resins, ASA resins, AES resins, and SAN resins ) are melted and kneaded by an extruder to produce a heat-resistant resin composition.

Since the maleimide-based copolymer of the present invention has excellent dispersibility, it has sufficient dispersibility in a resin such as an ABS resin. For this reason, even under conditions of a high discharge rate using a deep-grooved screw with slightly inferior dispersibility, the maleimide-based copolymer is well dispersed, and a molded product free from poor appearance can be obtained.

It is a screw configuration diagram of a twin-screw extruder according to an embodiment of the present invention.

<Description of terms>
In the specification of the present application, for example, the description “A to B” means A or more and B or less.

Hereinafter, embodiments of the present invention will be described in detail. The embodiments shown below can be combined with each other.

The maleimide-based copolymer of the present invention has an average particle size of 70 μm or more, and less than 5% by mass of 1000 μm or more on a sieve.

The maleimide-based copolymer (A) is a copolymer having maleimide-based monomer units and styrene-based monomer units. The present invention may further contain acrylonitrile-based monomer units and unsaturated dicarboxylic acid anhydride-based monomer units.

Maleimide-based monomer units include, for example, N-methylmaleimide, N-butylmaleimide, N-alkylmaleimide such as N-cyclohexylmaleimide, N-phenylmaleimide, N-chlorophenylmaleimide, N-methylphenylmaleimide, N-methoxyphenylmaleimide, N-tribromophenylmaleimide and the like. Among these, N-phenylmaleimide is preferred. The maleimide-based monomer units may be used alone or in combination of two or more. As for the maleimide-based monomer unit, for example, a raw material comprising a maleimide-based monomer can be used. Alternatively, it can be obtained by imidizing a raw material composed of unsaturated dicarboxylic acid monomer units with ammonia or a primary amine.
The maleimide-based copolymer (A) preferably contains 40 to 70% by mass, more preferably 45 to 60% by mass, of maleimide-based monomer units in 100% by mass of the maleimide-based copolymer (A). preferable. Specifically, for example, it is 40, 41, 42, 43, 44, 45, 50, 55, 60, or 70% by mass, and may be within a range between any two of the numerical values exemplified here. . If the content of the maleimide-based monomer unit is within this range, the compatibility with at least one resin (B) selected from ABS resin, ASA resin, AES resin, and SAN resin, which will be described later, is improved. , the impact strength of the resin composition is excellent. The content of maleimide-based monomer units is a value measured by 13C-NMR.

Styrenic monomer units include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, ethylstyrene, p-tert-butylstyrene, α-methylstyrene, α- and methyl-p-methylstyrene. Among these, styrene is preferred. The styrene-based monomer units may be used alone or in combination of two or more.
The maleimide-based copolymer (A) preferably contains 20 to 60% by mass, more preferably 35 to 55% by mass, of styrene-based monomer units in 100% by mass of the maleimide-based copolymer (A). preferable. Specifically, for example, 20, 30, 40, 45, 46, 47, 48, 49, 50, 55, or 60% by mass, and within the range between any two of the numerical values exemplified here good too. When the content of the styrene-based monomer unit is within this range, the compatibility with at least one resin (B) selected from ABS resin, ASA resin, AES resin, and SAN resin, which will be described later, is improved. , the impact strength of the resin composition is excellent. The content of styrene-based monomer units is a value measured by 13C-NMR.

Acrylonitrile-based monomer units include acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile, and the like. Among these, acrylonitrile is preferred. Acrylonitrile-based monomer units may be used alone, or two or more of them may be used in combination.
The maleimide-based copolymer (A) preferably contains 0 to 20% by mass of acrylonitrile-based monomer units in 100% by mass of the maleimide-based copolymer (A), and may contain 0 to 15% by mass. preferable. Specifically, for example, it is 0, 5, 6, 7, 8, 9, 10, 15, or 20% by mass, and may be within a range between any two of the numerical values exemplified here. If the content of the acrylonitrile-based monomer unit is within this range, the chemical resistance of the resin composition will be excellent. The content of acrylonitrile-based monomer units is a value measured by 13C-NMR.

The unsaturated dicarboxylic anhydride monomer units include maleic anhydride, itaconic anhydride, citraconic anhydride, and aconitic anhydride. Among these, maleic anhydride is preferred. The unsaturated dicarboxylic anhydride-based monomer units may be used alone or in combination of two or more.
The maleimide-based copolymer (A) preferably contains 0 to 10% by mass of unsaturated dicarboxylic anhydride-based monomer units in 100% by mass of the maleimide-based copolymer (A), and preferably 0 to 5% by mass. % is preferable. Specifically, for example, it is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% by mass, and within the range between any two of the numerical values illustrated here good too. When the content of the unsaturated dicarboxylic acid anhydride-based monomer unit is within this range, the thermal stability of the maleimide-based copolymer is excellent. The content of unsaturated dicarboxylic acid anhydride-based monomer units is a value measured by a titration method.

The maleimide-based copolymer (A) in one aspect of the present invention contains 40 to 70% by mass of maleimide-based monomer units and 20% by mass of styrene-based monomer units in 100% by mass of the maleimide-based copolymer (A). It preferably contains up to 60% by mass, 0 to 20% by mass of acrylonitrile-based monomer units, and 0 to 10% by mass of unsaturated dicarboxylic acid anhydride-based monomer units. More preferably, 45 to 60% by mass of maleimide-based monomer units, 35 to 55% by mass of styrene-based monomer units, and acrylonitrile-based monomer units in 100% by mass of the maleimide-based copolymer (A) 0 to 15% by mass, and 0 to 5% by mass of unsaturated dicarboxylic acid anhydride-based monomer units. If the structural unit is within the above range, the maleimide-based copolymer (A) will be excellent in fluidity, heat resistance, and thermal stability.

In terms of efficiently improving the heat resistance of at least one resin (B) selected from ABS resins, ASA resins, AES resins, and SAN resins, which will be described later, the glass transition of the maleimide-based copolymer (A) The temperature (Tmg) is preferably 170-210°C, more preferably 185-205°C. The glass transition temperature is a value measured by DSC under the measurement conditions described below.
Device name: Robot DSC6200 manufactured by Seiko Instruments Inc.
Heating rate: 10°C/min

The weight average molecular weight (Mw) of the maleimide-based copolymer (A) is preferably 60,000 to 150,000, more preferably 70,000 to 140,000. Specifically, it is, for example, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 150,000, and may be within a range between any two of the numerical values exemplified here. When the weight-average molecular weight (Mw) of the maleimide-based copolymer (A) is within the above range, the resin composition obtained by melt-kneading with the resin (B) described later has an excellent balance between fluidity and impact strength. In order to control the weight average molecular weight (Mw) of the maleimide-based copolymer (A), in addition to adjusting the polymerization temperature, the polymerization time, and the amount of the polymerization initiator added, the solvent concentration and the amount of the chain transfer agent added are adjusted. There are other methods. The weight average molecular weight of the maleimide-based copolymer (A) is a polystyrene-equivalent value measured by gel permeation chromatography (GPC), and was measured under the following conditions.
Device name: SYSTEM-21 Shodex (manufactured by Showa Denko)
Column: 3 PL gel MIXED-B in series Temperature: 40°C
Detection: Differential refractive index Solvent: Tetrahydrofuran Concentration: 2% by mass
Calibration curve: prepared using standard polystyrene (PS) (manufactured by PL).

A known method can be employed as a method for producing the maleimide-based copolymer (A). For example, there is a method of copolymerizing a monomer mixture comprising styrene-based monomers, maleimide-based monomers, unsaturated dicarboxylic acid anhydride-based monomers, and other copolymerizable monomers. After copolymerizing a monomer mixture consisting of a styrene-based monomer, an unsaturated dicarboxylic anhydride-based monomer, and other copolymerizable monomers, the unsaturated dicarboxylic anhydride-based monomer unit part of is reacted with ammonia or a primary amine to imidize and convert to maleimide-based monomer units (hereinafter referred to as "post-imidation method").

Polymerization modes of the maleimide-based copolymer (A) include, for example, solution polymerization and bulk polymerization. Solution polymerization is preferable from the viewpoint that a maleimide-based copolymer (A) having a more uniform copolymer composition can be obtained by polymerizing while performing partial addition or the like. The solvent for solution polymerization is preferably non-polymerizable from the viewpoint that by-products are less likely to occur and adverse effects are less likely to occur. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetophenone, ethers such as tetrahydrofuran and 1,4-dioxane, aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, N,N-dimethylformamide, dimethyl Examples include sulfoxide and N-methyl-2-pyrrolidone, and methyl ethyl ketone and methyl isobutyl ketone are preferred from the standpoint of ease of solvent removal during devolatilization recovery of the maleimide copolymer (A). Any of a continuous polymerization system, a batch system (batch system), and a semi-batch system can be applied to the polymerization process. The polymerization method is not particularly limited, but radical polymerization is preferable from the viewpoint of being able to produce with high productivity by a simple process.

In solution polymerization or bulk polymerization, a polymerization initiator and a chain transfer agent can be used, and the polymerization temperature is preferably in the range of 80 to 150°C. Polymerization initiators include, for example, azo compounds such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, azobismethylproponitrile, azobismethylbutyronitrile, benzoyl peroxide, t-butyl peroxybenzoate, 1 , 1-di(t-butylperoxy)cyclohexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxide, dicumylperoxide, ethyl- Peroxides such as 3,3-di-(t-butylperoxy)butyrate, which may be used alone or in combination of two or more. From the viewpoint of polymerization reaction rate and polymerization rate control, it is preferable to use an azo compound or an organic peroxide having a 10-hour half-life of 70 to 120°C. The amount of the polymerization initiator used is not particularly limited, but it is preferable to use 0.1 to 1.5% by mass based on 100% by mass of the total monomer units, more preferably 0.1 to It is 1.0% by mass. If the amount of the polymerization initiator used is 0.1% by mass or more, a sufficient polymerization rate can be obtained, which is preferable. When the amount of the polymerization initiator used is 1.5% by mass or less, the polymerization rate can be suppressed, so the reaction control becomes easy, and the target molecular weight can be easily obtained. Chain transfer agents include, for example, n-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, α-methylstyrene dimer, ethyl thioglycolate, limonene, terpinolene and the like. The amount of the chain transfer agent used is not particularly limited as long as the target molecular weight is obtained, but it is 0.1 to 0.8% by mass with respect to 100% by mass of the total monomer units. is preferred, and more preferably 0.15 to 0.5% by mass. If the amount of chain transfer agent used is 0.1% by mass to 0.8% by mass, the target molecular weight can be easily obtained.

Introduction of the maleimide-based monomer unit into the maleimide-based copolymer (A) includes a method of copolymerizing a maleimide-based monomer and a post-imidization method. The post-imidation method is preferable because the amount of residual maleimide monomer in the maleimide copolymer (A) is reduced. The post-imidization method involves copolymerizing a monomer mixture consisting of a styrene-based monomer, an unsaturated dicarboxylic anhydride-based monomer, and other copolymerizable monomers, and then adding an unsaturated dicarboxylic acid. In this method, part of the anhydride-based monomer units are reacted with ammonia or a primary amine to imidize them and convert them into maleimide-based monomer units. Primary amines include, for example, alkylamines such as methylamine, ethylamine, n-propylamine, iso-propylamine, n-butylamine, n-pentylamine, n-hexylamine, n-octylamine, cyclohexylamine and decylamine. Amines and aromatic amines such as chloro- or bromo-substituted alkylamines, aniline, toluidine, naphthylamine, among which aniline is preferred. These primary amines may be used alone or in combination of two or more. During the post-imidization, a catalyst can be used to improve the dehydration ring closure reaction in the reaction between the primary amine and the unsaturated dicarboxylic acid anhydride-based monomer unit. Catalysts are, for example, tertiary amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, N,N-dimethylaniline, N,N-diethylaniline. The temperature for post-imidization is preferably 100 to 250°C, more preferably 120 to 200°C. If the imidization reaction temperature is 100° C. or higher, the reaction rate is improved, which is preferable from the viewpoint of productivity. If the temperature of the imidization reaction is 250° C. or lower, it is possible to suppress deterioration in physical properties due to thermal deterioration of the maleimide copolymer (A), which is preferable.

A method of removing volatile components such as the solvent used in the solution polymerization and unreacted monomers from the solution after the solution polymerization of the maleimide copolymer (A) has been completed or the solution after the post-imidation has been completed (devolatilization method). can employ a known method. For example, a vacuum devolatilization tank with a heater or a devolatilization extruder with a vent can be used. The devolatilized molten maleimide copolymer (A) is transferred to a granulation process, extruded into strands from a multi-hole die, and pelletized by a cold cut method, an air hot cut method, or an underwater hot cut method. can be processed.

The pellet-shaped maleimide-based copolymer (A) can be processed into powder by using a known pulverizer. The pulverizer includes, for example, a screen-type pulverizer and an impact-type pulverizer.

The maleimide-based copolymer (A) is powdery and has an average particle size of 75 μm or more, preferably 80 to 300 μm, more preferably 100 to 250 μm. Specifically, for example, 75, 80, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290 or 300 μm, and may be in the range between any two of the values exemplified here. By powdering, the dispersibility during melt extrusion kneading is greatly improved, but if the average particle size is less than 75 μm, clogging may occur in the feed zone of the extruder when the material is fed from the hopper. There is It also increases the risk of dust explosion. The average particle size of the powder can be measured using a JIS Z 8801 test sieve. Using sieves with mesh openings of 1000, 850, 500, 355, 250, 150, 106, 75, and 50 μm, 50 g of maleimide-based copolymer powder mixed by spraying an antistatic agent is put into the sieve with the largest opening. Put the lid on the shaker, set the sieve on the shaker, shake for 20 minutes, measure the mass of each sieve containing the powder, and subtract the mass of the sieve to calculate the particle size distribution on the sieve. can. From the results of the particle size distribution, the mass is added in order from the larger opening, and the particle diameter obtained from the intersection of the two points of opening (particle diameter) and 50% sandwiching the cumulative mass of 50% is the average particle diameter. and For example, when using a screen-type pulverizer, the average particle size can be adjusted by adjusting the screen diameter and rotation speed.

The amount of the powdery maleimide-based copolymer (A) on a 1000 μm sieve is less than 5% by mass, preferably less than 3% by mass. In the definition of the particle amount of the maleimide-based copolymer in the present invention, "on the sieve" means the cumulative distribution representing the percentage of the total amount of particles having a specific particle diameter or larger. In addition, the term "under sieve" in the definition of the particle amount of the maleimide copolymer in the present invention means the cumulative distribution representing the percentage of the total amount of particles having a specific particle diameter or less. Specifically, for example, less than 5, 4, 3, 2, or 1% by weight on a 1000 μm sieve, and may be within a range between any two of the values exemplified herein. If the content on a 1000 µm sieve exceeds 5% by mass, the dispersibility during melt extrusion kneading deteriorates even in powder form. The content on a 1000 μm sieve can be adjusted by the grinding conditions and the classification after grinding. The content from the top of the 75 μm sieve to the bottom of the 850 μm sieve is preferably 60 to 90% by mass, more preferably 65 to 90% by mass. Specifically, for example, it is 60, 65, 70, 75, 80, 85, or 90% by mass, and may be within a range between any two of the numerical values exemplified here.

As the maleimide-based copolymer (A), one containing a large amount of maleimide-based monomer units may be used from the viewpoint of imparting heat resistance to the resin (B). In such a case, the melt viscosity of the maleimide-based copolymer (A) increases due to an increase in the content of maleimide-based monomer units, which may cause a problem in dispersibility when melt-kneaded with the resin (B). be. With the maleimide-based copolymer (A) according to the present invention, the resin ( Excellent dispersibility when melt-kneaded with B).
When using a maleimide-based copolymer (A) containing a large amount of maleimide-based monomer units from the viewpoint of imparting heat resistance to the resin (B), the maleimide-based copolymer (A) at 260°C and a shear rate of 120/ The melt viscosity at 260°C and a shear rate of 120/sec is preferably 1000 Pa·s or more, and the melt viscosity at 280°C and a shear rate of 120/sec is preferably 1000 Pa·s or more. is 500 Pa·s or more. The higher the melt viscosity of the maleimide-based copolymer (A), the worse the dispersibility during melt extrusion kneading, but the effect of improving the dispersibility by making it powdery also increases. From the viewpoint of dispersibility, the melt viscosity of the maleimide-based copolymer (A) at 280° C. and a shear rate of 120/sec is preferably 3000 Pa·s or less, more preferably 2000 Pa·s or less. The melt viscosity is a value measured using a capillary rheometer with a capillary die of L=40 mm and D=1 mm.

The resin (B) is selected from ABS resin, ASA resin, AES resin and SAN resin, and may be of one type or two or more types.

ABS resin, ASA resin, and AES resin are graft copolymers obtained by graft-copolymerizing a rubber-like polymer with at least a styrene-based monomer and an acrylonitrile-based monomer. For example, when using butadiene-based rubber such as polybutadiene and styrene-butadiene copolymer as the rubber-like polymer, ABS resin is used, and when using acrylic rubber made of butyl acrylate, ethyl acrylate, etc., ASA resin, ethylene- AES resin is used when ethylene rubber such as α-olefin copolymer is used. At the time of graft copolymerization, two or more of these rubber-like polymers may be used in combination.

A known method can be employed as a method for producing a graft copolymer such as an ABS resin. For example, a production method by emulsion polymerization or continuous bulk polymerization can be mentioned. A method by emulsion polymerization is preferable because it is easy to adjust the content of the rubber-like polymer in the final resin composition.

A method for producing a graft copolymer by emulsion polymerization includes a method in which a styrene-based monomer and an acrylonitrile-based monomer are emulsion-graft-polymerized in a latex of a rubber-like polymer (hereinafter referred to as "emulsion graft polymerization method"). ). A latex of a graft copolymer can be obtained by an emulsion graft polymerization method.

In the emulsion graft polymerization method, water, an emulsifier, a polymerization initiator and a chain transfer agent are used, and the polymerization temperature is preferably in the range of 30 to 90°C. Examples of emulsifiers include anionic surfactants, onionic surfactants, and amphoteric surfactants. Polymerization initiators include, for example, organic peroxides such as cumene hydroperoxide, diisopropylene peroxide, t-butylperoxyacetate, t-hexylperoxybenzoate, and t-butylperoxybenzoate, potassium persulfate, and ammonium persulfate. azo compounds such as azobisbutyronitrile; reducing agents such as iron ions; secondary reducing agents such as sodium formaldehyde sulfoxylate; and chelating agents such as disodium ethylenediaminetetraacetate. Chain transfer agents include, for example, n-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, α-methylstyrene dimer, ethyl thioglycolate, limonene, terpinolene and the like.

The graft copolymer latex can be coagulated by a known method to recover the graft copolymer. For example, a coagulant is added to the latex of the graft copolymer to coagulate it, followed by washing and dehydration with a dehydrator, followed by drying to obtain a powdery graft copolymer.

The content of the rubber-like polymer in the graft copolymer obtained by the emulsion graft polymerization method is preferably 40 to 70% by mass, more preferably 45 to 65% by mass, from the viewpoint of impact resistance. . The content of the rubber-like polymer can be adjusted, for example, by adjusting the ratio of the styrene-based monomer and the acrylonitrile-based monomer to the rubber-like polymer used during emulsion graft polymerization.

From the viewpoint of impact resistance and chemical resistance, the constituent units excluding the rubber-like polymer of the graft copolymer obtained by the emulsion graft polymerization method include 65 to 85% by mass of styrene-based monomer units and acrylonitrile-based monomers. The body unit content is preferably 15 to 35% by mass.

The gel content of the graft copolymer is preferably particulate. The gel content is particles of a rubber-like polymer obtained by graft copolymerization of a styrene-based monomer and an acrylonitrile-based monomer, and is a component that is insoluble in organic solvents such as methyl ethyl ketone and toluene and separated by centrifugation. An occlusion structure in which the styrene-acrylonitrile copolymer is encapsulated in the form of particles may be formed inside the particles of the rubber-like polymer. When the graft copolymer and the styrene-acrylonitrile copolymer are melt-blended, the gel fraction exists as a particulate dispersed phase in the continuous phase of the styrene-acrylonitrile copolymer. The gel content is obtained by dissolving the graft copolymer having a mass of W in methylethylene ketone, centrifuging at 20000 rpm using a centrifuge to precipitate the insoluble matter, and removing the supernatant by decantation to obtain the insoluble matter. It is a value calculated from the mass S of the dried insoluble matter after vacuum drying by the formula: gel content (mass%) = (S/W) x 100. Also, the gel content can be calculated by similarly dissolving the resin composition obtained by melt-blending the graft copolymer and the styrene-acrylonitrile copolymer in methyl ethyl ketone and centrifuging.

The volume average particle size of the gel portion of the graft copolymer is preferably in the range of 0.10 to 1.0 μm, more preferably 0.15 to 0.1 μm, from the viewpoint of impact resistance and appearance of molded articles. 50 μm. The volume-average particle size is obtained by cutting an ultra-thin section from pellets of a resin composition obtained by melt-blending a graft copolymer and a styrene-acrylonitrile copolymer, observing it with a transmission electron microscope (TEM), and dispersing it in the continuous phase. It is a value calculated from image analysis of the particles obtained. The volume average particle size can be adjusted, for example, by the particle size of the latex of the rubber-like polymer used in the emulsion graft polymerization. The particle size of the latex of the rubber-like polymer can be adjusted by the addition method of the emulsifier and the amount of water used during the emulsion polymerization. There is a method in which a rubber-like polymer having a particle size of about 1 μm is polymerized in a short period of time and the rubber particles are enlarged by using a chemical coagulation method or a physical coagulation method.

The graft ratio of the graft copolymer is preferably 10 to 100% by mass, more preferably 20 to 70% by mass, from the viewpoint of impact resistance. The graft ratio is a value calculated from the gel content (G) and the content (RC) of the rubber-like polymer by graft ratio (% by mass)=[(G-RC)/R]×100. Graft ratio is the amount of styrene-acrylonitrile copolymer bound by grafts contained in rubber-like polymer particles per unit mass of rubber-like polymer and the amount of styrene-acrylonitrile copolymer included in particles. show. For example, when emulsion graft polymerization is performed, the graft rate is determined by the ratio of the monomer to the rubber-like polymer, the type and amount of the initiator, the amount of the chain transfer agent, the amount of the emulsifier, the polymerization temperature, and the charging method (batch/multistage/continuous). , the addition rate of the monomer, and the like.

The toluene swelling degree of the graft copolymer is preferably 5 to 20 times from the viewpoint of impact resistance and molded product appearance. The degree of swelling in toluene represents the degree of cross-linking of rubber-like polymer particles. is calculated from the mass ratio of the dry state after removing The degree of swelling of toluene is affected by, for example, the degree of cross-linking of the rubber-like polymer used in the emulsion graft polymerization, which depends on the initiator, emulsifier, polymerization temperature, divinylbenzene, etc. in the emulsion polymerization of the rubber-like polymer. It can be adjusted by adding a polyfunctional monomer or the like.

SAN resin is a copolymer having styrene-based monomer units and acrylonitrile-based monomer units, such as a styrene-acrylonitrile copolymer.

Other copolymerizable monomers for the SAN resin include (meth)acrylic acid ester-based monomers such as methyl methacrylate, acrylic acid ester-based monomers such as butyl acrylate and ethyl acrylate, methacrylic acid, and the like. (Meth)acrylic acid-based monomers, acrylic acid-based monomers such as acrylic acid, and N-substituted maleimide-based monomers such as N-phenylmaleimide can be used.

The constituent units of the SAN resin preferably contain 60 to 90% by mass of styrene monomer units and 10 to 40% by mass of vinyl cyanide monomer units, more preferably 65 to 80% by mass of styrene monomer units. % by mass, vinyl cyanide monomer unit is 20 to 35% by mass. If the structural unit is within the above range, the resulting resin composition will have an excellent balance between impact strength and fluidity. Styrenic monomer units and vinyl cyanide monomer units are values measured by 13C-NMR.

A known method can be employed as a method for producing the SAN resin. For example, it can be produced by bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, or the like. As for the operating method of the reactor, any of a continuous system, a batch system (batch system), and a semi-batch system can be applied. Bulk polymerization or solution polymerization is preferred from the aspects of quality and productivity, and continuous polymerization is preferred. Examples of solvents for bulk polymerization or solution polymerization include alkylbenzenes such as benzene, toluene, ethylbenzene and xylene, ketones such as acetone and methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and cyclohexane.

In bulk polymerization or solution polymerization of SAN resin, a polymerization initiator and a chain transfer agent can be used, and the polymerization temperature is preferably in the range of 120 to 170°C. Polymerization initiators include, for example, 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, 2,2-di(4,4-di-t-butyl peroxycyclohexyl)propane, peroxyketals such as 1,1-di(t-amylperoxy)cyclohexane, hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide, t-butyl peroxyacetate , alkyl peroxides such as t-amyl peroxy isononanoate, dialkyl peroxides such as t-butyl cumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, di-t-hexyl peroxide, Peroxy esters such as t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxy isopropyl monocarbonate, t-butyl peroxy isopropyl carbonate, polyether tetrakis (t-butyl peroxy carbonate), etc. Peroxycarbonates, N,N'-azobis(cyclohexane-1-carbonitrile), N,N'-azobis(2-methylbutyronitrile), N,N'-azobis(2,4-dimethylvaleronitrile) , N,N'-azobis[2-(hydroxymethyl)propionitrile] and the like, and these may be used alone or in combination of two or more. Chain transfer agents include, for example, n-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, α-methylstyrene dimer, ethyl thioglycolate, limonene, terpinolene and the like.

As a devolatilization method for removing volatile components such as unreacted monomers and the solvent used in the solution polymerization from the solution after polymerization of the SAN resin, a known technique can be employed. For example, a vacuum devolatilization tank with a preheater or a devolatilization extruder with a vent can be used. The devolatilized molten SAN resin is transferred to a granulation step, extruded in a strand form from a multi-hole die, and processed into pellets by a cold cut method, an air hot cut method, or an underwater hot cut method.

The weight average molecular weight of the SAN resin is preferably 50,000 to 250,000, more preferably 70,000 to 200,000, from the viewpoint of impact resistance and moldability of the resin composition. Specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 200,000. It may be in a range between the two. The weight average molecular weight of the SAN resin is a polystyrene-equivalent value measured in a THF solvent using gel permeation chromatography (GPC), and is a value measured in the same manner as for the maleimide-based copolymer (A). be. The weight average molecular weight can be adjusted by the type and amount of chain transfer agent during polymerization, solvent concentration, polymerization temperature, and type and amount of polymerization initiator.

As the resin (B), for example, a method of using two types of powdery ABS resin obtained by an emulsion polymerization method and a pellet-like SAN resin obtained by a continuous bulk polymerization method can be used. Alternatively, a powdery ABS resin obtained by emulsion polymerization and a pelletized SAN resin obtained by continuous bulk polymerization are once melt-blended using an extruder or the like to obtain a pelletized ABS resin. method.

The method of melt-kneading the maleimide-based copolymer (A) and at least one resin (B) selected from ABS resin, ASA resin, AES resin, and SAN resin using an extruder is a known method. can be adopted. A known extruder can be used, and examples thereof include a twin-screw extruder, a single-screw extruder, a multi-screw extruder, and a continuous kneader with a twin-screw rotor. It is preferred to use a twin-screw extruder, intermeshing co-rotating twin-screw extruders being more commonly used and more preferred.

As the screw of the twin-screw extruder in the embodiment of the present invention, it is preferable to use a screw having a large screw depth-to-groove ratio from the viewpoint of productivity. The screw depth ratio is defined by the ratio D/d of the screw outer diameter (D) and root diameter (d). The screw depth ratio may be uniform throughout the screw or may be different in each section. The screw depth ratio in the kneading section of the present invention is the screw depth ratio in the section where the mixing element is arranged and the temperature is the highest among the sections where the material to be melt-kneaded is kneaded. In the embodiment of the present invention, from the viewpoint of productivity, the screw depth/groove ratio in the kneading section of the twin-screw extruder is preferably 1.55 or more.

Melt-kneading is preferably carried out in the presence of an antioxidant (C). A hindered phenol-based antioxidant is preferably used as the antioxidant, and a phosphorus-based antioxidant may be used in combination.

A hindered phenol-based antioxidant is an antioxidant having a phenolic hydroxyl group in its basic skeleton. Hindered phenolic antioxidants include, for example, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, ethylenebis(oxyethylene)bis[3-(5-tert-butyl- 4-hydroxy-m-tolyl)propionate], 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl]- 2,4,8,10-tetraoxaspiro[5.5]undecane, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 4,6-bis(octyl thiomethyl)-o-cresol, 4,6-bis[(dodecylthio)methyl]-o-cresol, 2,4-dimethyl-6-(1-methylpentadecyl)phenol, tetrakis[methylene-3-(3, 5-di-t-butyl-4-hydroxyphenyl)propionate]methane, 4,4′-thiobis(6-t-butyl-3-methylphenol), 1,1,3-tris(2-methyl-4- Hydroxy-5-t-butylphenyl)butane, 4,4′-butylidenebis(3-methyl-6-t-butylphenol), bis-[3,3-bis-(4′-hydroxy-3′-tert-butyl phenyl)-butanoic acid]-glycol ester, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2-[1-(2-hydroxy -3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate and the like. Preferably, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl) propionate], and pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. More preferred is octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. The hindered phenol-based antioxidants may be used alone or in combination of two or more.

Phosphorus-based antioxidants are phosphites, which are trivalent phosphorus compounds. Phosphorus-based antioxidants include, for example, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butylbenz [d, f ][1,3,2]dioxaphosphepine, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9- Diphosphaspiro[5.5]undecane, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, 2,2′-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyl) oxy) phosphorous, tris(2,4-di-tert-butylphenyl)phosphite, bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethyl ester phosphorous acid, bis(2 ,4-di-tert-butylphenyl)pentaerythritol diphosphite, cyclic neopentanetetrayl bis(octadecylphosphite), bis(nonylphenyl)pentaerythritol diphosphite, 4,4'-biphenylene diphosphinic acid tetrakis ( 2,4-di-tert-butylphenyl), 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakis(2,4-di-tert-butyl-5-methylphenyl)- 4,4'-biphenylene diphosphonite and the like. Preferably, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butylbenz[d,f][1,3, 2] dioxaphosphepine, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] Undecane, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, 2,2′-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, tris ( 2,4-di-tert-butylphenyl)phosphite and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite. More preferably, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butylbenz[d,f][1,3 ,2] dioxaphosphepine, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert -butylphenyl)pentaerythritol diphosphite, more preferably 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t -butylbenz[d,f][1,3,2]dioxaphosphepine, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)penta Erythritol diphosphite. Phosphorus-based antioxidants may be used alone or in combination of two or more.

When the cylinder temperature of the kneading section is 290° C. or higher, it is preferable to further use a radical scavenger as the antioxidant (C). Radical scavengers include 2-t-butyl-6-(3′-t-butyl-5′-methyl-2′-hydroxybenzyl)-4-methylphenylacrylate, 2,4-di-t-amyl- 6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate.

The amount of the antioxidant (C) added is preferably 0.1 to 0.5 parts by mass, more preferably 100 parts by mass in total of the maleimide copolymer (A) and the resin (B). is 0.3 to 0.5 parts by mass. Specifically, for example, it is 0.1, 0.2, 0.3, 0.4, or 0.5 parts by mass, and may be within a range between any two of the numerical values exemplified here. .

The content of the maleimide-based copolymer (A) in the resin composition is 5 to 45% by mass when the total amount of the maleimide-based copolymer (A) and the resin (B) is 100% by mass. is preferred, more preferably 7 to 35% by mass, still more preferably 10 to 30% by mass. Specifically, for example, 5, 10, 15, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, or 45% by mass, the numerical values illustrated here may be in the range between any two of If the content of the maleimide-based copolymer (A) is too small, the heat resistance of the resin composition may not be sufficiently improved. If the amount is too large, fluidity may decrease and moldability may deteriorate. The resin contained in the resin composition may be substantially only the maleimide copolymer (A) and the resin (B).

When producing the heat-resistant resin composition, other resin components, impact modifiers, fluidity modifiers, hardness modifiers, antioxidants, inorganic fillers, luster are added to the extent that the effects of the present invention are not impaired. Extinguisher, flame retardant, auxiliary flame retardant, anti-drip agent, slidability agent, heat dissipation material, electromagnetic wave absorber, plasticizer, lubricant, release agent, ultraviolet absorber, light stabilizer, antibacterial agent, antifungal agent agents, antistatic agents, carbon black, titanium oxide, pigments, dyes and the like may be added.

Detailed contents will be described below using examples, but the present invention is not limited to the following examples.

<Production Example of Maleimide Copolymer (A-1)>
A maleimide-based copolymer (A-1) was produced by the following method.
62 parts by mass of styrene, 11 parts by mass of maleic anhydride, 0.2 parts by mass of 2,4-diphenyl-4-methyl-1-pentene, and 31 parts by mass of methyl ethyl ketone were placed in an autoclave having a volume of about 120 liters equipped with a stirrer. After charging and replacing the inside of the system with nitrogen gas, the temperature was raised to 92° C., and 28 parts by mass of maleic anhydride and 0.19 parts by mass of t-butyl peroxy-2-ethylhexanoate were added to 110 parts by mass of methyl ethyl ketone. The solution dissolved in parts was added continuously over 7 hours. After the addition, the temperature was raised to 120° C. and the reaction was allowed to proceed for 30 minutes to complete the polymerization. After that, 35 parts by mass of aniline and 0.6 parts by mass of triethylamine were added to the polymerization liquid and reacted at 140° C. for 7 hours. After completion of the reaction, the imidization reaction solution was put into a vent-type screw extruder, and volatile components were removed to obtain a maleimide copolymer (A-1) in the form of pellets of about 3 mm. A-1 contained 48% by mass of styrene units, 51% by mass of N-phenylmaleimide units and 1% by mass of maleic anhydride units, and had a weight average molecular weight Mw of 130,000 and a glass transition temperature Tmg of 202°C. Further, the melt viscosity at 260° C. and a shear rate of 120/sec was 3420 Pa·s, and the melt viscosity at 280° C. and a shear rate of 120/sec was 1780 Pa·s.

<Production Examples of Maleimide Copolymers (A-2 to A-8)>
Using a screen-type pulverizer, the maleimide copolymer (A-1) was pulverized into powder. With a screen diameter of 1 mm, A-2 to A-5 having different average particle diameters were obtained by changing the number of revolutions. A-6 was obtained by removing the sieve (850 μm) of A-4. A-7 was used under a sieve (75 μm) only. A-8 was a mixture of 80% by mass of A-2 and 10% by mass of A-6 on a sieve (1000 μm). The average particle size of the powder was measured using a JIS Z 8801 test sieve. Using sieves with mesh openings of 1000, 850, 500, 355, 250, 150, 106, 75, and 50 μm, 50 g of maleimide-based copolymer powder mixed by spraying an antistatic agent is put into the sieve with the largest opening. Then, the sieve was placed on the shaker and shaken for 20 minutes. After shaking, the mass of each sieve containing the powder was measured and the mass of the sieve was subtracted to calculate the particle size distribution on the sieve. From the results of the particle size distribution, the mass is added in order from the larger opening, and the particle diameter obtained from the intersection of the two points of opening (particle diameter) and 50% sandwiching the cumulative mass of 50% is the average particle diameter. and The average particle size of A-7 was less than 75 μm because the average particle size could not be measured by this measurement method, but the average particle size determined by the laser diffraction/scattering method was 37 μm.

<Production Example of Maleimide Copolymer (A-9)>
A maleimide-based copolymer (A-9) was produced by the following method.
In an autoclave having a volume of about 120 liters equipped with a stirrer, 42 parts by weight of styrene, 10 parts by weight of acrylonitrile, 4 parts by weight of maleic anhydride, 0.03 parts by weight of 2,4-diphenyl-4-methyl-1-pentene, After 27 parts by mass of methyl ethyl ketone was charged and the gas phase was replaced with nitrogen gas, the temperature was raised to 92° C. over 40 minutes while stirring. While maintaining the temperature at 92° C. after raising the temperature, a solution of 21 parts by mass of maleic anhydride and 0.15 parts by mass of t-butyl peroxy-2-ethylhexanoate dissolved in 85 parts by mass of methyl ethyl ketone and 20 parts by mass of styrene were added. It was added continuously over 4.5 hours. After addition of maleic anhydride, a solution of 0.02 parts by mass of t-butyl peroxy-2-ethylhexanoate dissolved in 9 parts by mass of methyl ethyl ketone and 3 parts by mass of styrene were continuously added over 30 minutes. . After the addition, the temperature was raised to 120° C. and the reaction was allowed to proceed for 30 minutes to complete the polymerization. After that, 23 parts by mass of aniline and 0.4 parts by mass of triethylamine were added to the polymerization liquid and reacted at 140° C. for 7 hours. After completion of the reaction, the imidization reaction solution was put into a vent-type screw extruder, and volatile components were removed to obtain a maleimide copolymer (A-9) in the form of pellets. Further, in the same manner as in (A-2) to (A-8), a screen-type pulverizer was used to pulverize the maleimide copolymer (A-9) into powder. (A-9) contains 52% by mass of styrene units, 8% by mass of acrylonitrile units, 39% by mass of N-phenylmaleimide units, and 1% by mass of maleic anhydride units, and has a weight average molecular weight Mw of 140,000 and a glass transition temperature Tmg. was 177°C. Further, the melt viscosity at 260° C. and a shear rate of 120/sec was 1660 Pa·s, and the melt viscosity at 280° C. and a shear rate of 120/sec was 710 Pa·s.

<ABS resin (B-1)>
A commercially available ABS resin (Denka ABS GR-3500 manufactured by Denka Co., Ltd.) was used.

<SAN Resin (B-2)>
A commercially available SAN resin (Denka AS AS-EXS manufactured by Denka Co., Ltd.) was used.

<Example/Comparative example>
The maleimide-based copolymer and the ABS resin were melt-kneaded using an extruder under the formulations and conditions shown in Table 1 to produce a heat-resistant resin composition. The extruder used was a twin-screw extruder (TEM-26SX manufactured by Toshiba Machine Co., Ltd.) having an L/D ratio of 48 and a screw depth ratio of 1.56. As antioxidants, the following (C-1) is 0.3 parts by mass and (C-2) is 0.15 parts by mass with respect to a total of 100 parts by mass of the maleimide copolymer (A) and the resin (B). Parts by mass were blended. Table 1 shows the evaluation results.

(C-1) Pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Irganox 1010 manufactured by BASF Japan Ltd.)
(C-2) Tris (2,4-di-tert-butylphenyl) phosphite (Irgafos 168 manufactured by BASF Japan Ltd.)

(melt mass flow rate)
The melt mass flow rate was measured at 220° C. under a load of 98 N according to JIS K7210.

(Vicat softening temperature)
The Vicat softening point was measured according to JIS K7206 by Method 50 (50 N load, 50° C./hour heating rate) using a test piece of 10 mm×10 mm and a thickness of 4 mm. In addition, the HDT & VSPT test equipment manufactured by Toyo Seiki Seisakusho Co., Ltd. was used as a measuring machine.

(Charpy impact strength)
The Charpy impact strength was measured according to JIS K7111-1, using notched test pieces and adopting an edgewise impact direction. A digital impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd. was used as the measuring machine.

(dispersion level)
Using an injection molding machine (IS-50EPN manufactured by Toshiba Machine Co., Ltd.), a mirror plate with a length of 90 mm, a width of 55 mm, and a thickness of 2 mm was molded under the molding conditions of a cylinder temperature of 220 ° C and a mold temperature of 60 ° C. The dispersed state of the copolymer was visually evaluated. If the dispersion state of the maleimide-based copolymer is poor, streaks along the flow of the resin are observed on the surface of the molded product.
Dispersion level 5: No defects, very clean appearance Dispersion level 4: Slightly fine streaks can be seen Dispersion level 3: Fine streaks can be seen Dispersion level 2: Streaks that cause obvious poor appearance are seen Dispersion level 1: Streaks that cause a clear appearance defect are seen on the entire surface

From the results of Table 1, by using a powdery maleimide copolymer having an average particle size of 75 μm or more and a sieve of 1000 μm or less of less than 5% by mass, the dispersibility of the maleimide copolymer was excellent. A heat-resistant resin composition is obtained.
Although not shown in Table 1, in Comparative Example 2, the feed zone of the extruder was clogged with the maleimide-based copolymer during the production of the heat-resistant resin composition, resulting in poor working efficiency.

By using the maleimide-based copolymer of the present invention, a heat-resistant resin composition having excellent dispersibility of the maleimide-based copolymer can be obtained with high productivity, and the appearance of the molded article thereof is also excellent.

Claims (5)

A powdery maleimide-based copolymer (A) having an average particle size of 75 to 300 μm and having a sieve of less than 5% by mass on a 1000 μm sieve. The maleimide-based copolymer (A) according to claim 1, which has a glass transition temperature of 170 to 210°C. 3. The maleimide copolymer (A) according to claim 1 or 2, which has a melt viscosity of 1000 Pa·s or more at 260° C. and a shear rate of 120/sec. The maleimide-based copolymer (A) according to any one of claims 1 to 3 , wherein the maleimide-based copolymer (A) has a weight average molecular weight (Mw) of 60,000 to 140,000. The maleimide-based copolymer (A) according to any one of claims 1 to 4 and at least one resin (B) selected from ABS resin, ASA resin, AES resin and SAN resin are extruded. A method for producing a heat-resistant resin composition by melt-kneading with.

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